html, body {
  height: 100%;
  margin: 0;
  background: #0b0f14;
  overflow: hidden;
  font-family: system-ui, -apple-system, Segoe UI, sans-serif;
}

canvas {
  display: block;
  width: 100vw;
  height: 100vh;
}

/* 画面左下のヒント */
.hint {
  position: fixed;
  left: 12px;
  bottom: 10px;
  font-size: 12px;
  color: rgba(255,255,255,0.55);
  user-select: none;
  pointer-events: none;
  text-shadow: 0 1px 8px rgba(0,0,0,0.6);
}

/* 右下の操作ボタン群 */
.controls {
  position: fixed;
  right: 12px;
  bottom: 10px;
  display: flex;
  gap: 8px;
}

.btn {
  font-size: 12px;
  color: rgba(255,255,255,0.85);
  background: rgba(255,255,255,0.08);
  border: 1px solid rgba(255,255,255,0.14);
  padding: 8px 10px;
  border-radius: 12px;
  cursor: pointer;
  user-select: none;
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
  transition: background 0.15s, transform 0.05s;
}

.btn:hover {
  background: rgba(255,255,255,0.12);
}

.btn:active {
  transform: translateY(1px);
}

/* JS無効時 */
.noscript {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: #000;
  color: #fff;
  font-size: 16px;
}

.visually-hidden {
  position: absolute !important;
  width: 1px; height: 1px;
  padding: 0; margin: -1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
  border: 0;
}